/**
 *       Copyright (c) 2012 Lukas Zaruba
 *
 *   This file is part of Robot Playground.
 *
 *   Robot Playground is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU Lesser General Public License as published by
 *   the Free Software Foundation, either version 3 of the License, or
 *   (at your option) any later version.
 *
 *   Robot Playground is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU Lesser General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public License
 *   along with Robot Playground. If not, see <http://www.gnu.org/licenses/>.
 */
package net.zarubsys.commons.scripting.functions.numbers;

import java.util.List;

import net.zarubsys.commons.scripting.IScriptFunction;
import net.zarubsys.commons.scripting.ParsedStatement;
import net.zarubsys.commons.scripting.ScriptingEnvironment;
import net.zarubsys.commons.scripting.ScriptingException;

/**
 * Based on scripting language from Media Solutions Slovakia, a.s.
 * @author Lukas Zaruba, lukas.zaruba@gmail.com
 */
public class RoundFunction implements IScriptFunction {

	@Override
	public int getMaxArgsNum() {
		return 2;
	}

	@Override
	public int getMinArgsNum() {
		return 1;
	}

	@Override
	public String getName() {
		return "round";
	}

	@Override
	public Object execute(ScriptingEnvironment env, List<ParsedStatement> args) throws ScriptingException {
		Object value = args.get(0).execute(env);
		Object precision = Integer.valueOf(0);
		if (args.size() > 1) {
			precision = args.get(1).execute(env);
			if (precision == null || !(precision instanceof Integer) || ((Integer) precision) < 0) {
				throw new IllegalArgumentException("Second argument of the " + getName() + " function has to be not-null non-negative Integer!");
			}
		}
		if (value == null || !(value instanceof Double)) throw new IllegalArgumentException("Argument of the " + getName() + " function has to be not-null Double!");
		Double number = (Double) value;
		if (((Integer) precision) == 0) {	//normal rounding
			return Math.round(number);
		}
		//shift, round, shift back
		long shiftValue = Math.round(Math.pow(10, (Integer) precision));
		return Double.valueOf(Math.round(number * shiftValue)) / shiftValue;
	}

}
